Noise problem on mx2424

[Antoine Colombani]

Hi,
I have a problem on my mx2424.
I get noise on track 19 when play, if track 20 play to. Track 20 works well. If track 20 play there is noise on 19 output.
I check db25, cable, this is not it.
I think problem comes output card, what do you think ?
Antoine

 

[witzendoz]

What output card have you got fitted?

Alan.

 

[Antoine Colombani]

This is the analog card.

Antoine

 

[witzendoz]

First thing to check is that there are clean contacts on the ribbon cables.

The next thing to check is the main caps, one of the cards I got hold of had been subjected to phantom power, someone connecting the MX analog card to a mixer with mic xlr's with the phantom on, a sure way to screw the card. I replaced the 48 caps and the board sprung back into life. It could be that one of the caps has leaked accross the board causing cross channel problems.

I used a different cap with better specs, here is a RS components link. A bit of a tight fit but OK.

Here are some photos of the work.

Alan.

 

[Antoine Colombani]

Hi,
I checked the contacts on the ribonn cable, and I replaced the 2 caps, the problem is not fixed.
It could be a common way on the circuit. I will search.

Antoine

 

[witzendoz]

When you say you replaced the 2 caps, do you mean on the noisy channel? I thought that you had noise caused by 2 channels, 19 and 20 as they seem to interact with each other. Just have a very good look at the circuit board around the 2 channels, there could be some contamination on the circuit board that is causing a short.

There could also be a dry or cracked solder joint in there somewhere. You will need a magnifying glass to see.

Alan.